From 2330820811dd594c7e799799288055a8b859a104 Mon Sep 17 00:00:00 2001
From: Jeff Yates <jeff@thinkpad.lab.doublehack.me>
Date: Tue, 15 Dec 2020 08:42:23 -0500
Subject: [PATCH] solved part 1

---
 day15/solution.rb | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100755 day15/solution.rb

diff --git a/day15/solution.rb b/day15/solution.rb
new file mode 100755
index 0000000..c8c1455
--- /dev/null
+++ b/day15/solution.rb
@@ -0,0 +1,18 @@
+#!/bin/env ruby
+require 'pry'
+numbers = File.read('./input').split(',')
+numbers.map!(&:to_i)
+
+2020.times do |i|
+    next if i < numbers.size
+    num = numbers[-1]
+    prev_turn = numbers[..-2].reverse.find_index(num)
+    if prev_turn == nil
+        numbers.push(0)
+    else
+        new_num = (i - 1) - (numbers.size - 2 - prev_turn)
+        numbers.push(new_num)
+    end
+end
+
+puts numbers[-1]
\ No newline at end of file